Yes, Oppo F9 does have the dual rear camera set up. The main camera has 16MP resolution while the second rear camera has a 2MP resolution.
No. Oppo F9 has MicroUSB port.
Yes, Oppo F9 does have the MicroSD card slot. You can expand memory up to 256GB.
Yes, Oppo F9 does have the face unlock.
The most striking feature of the Oppo F9 is the big display with the waterdrop notch. It is well designed, delivers good battery life, and offers decent performance for the price.